badinstincts

I think the offset on the stock rims is 45mm, so these new rims I want have an offset of 35mm, so what will happen? My wheels will stick out 10mm more? does that effect the ride, alignment or anything? What can be done?

badinstincts

ohh, the new rims i want are 17x7.5 and the stock are 16x7 so does that extra .5 inch fix the offset problem?

monkeytronic

17x7.5 ET35s should extend an additional 16mm further outboard than 16x7 ET45s.

The improvements in handling won't be attributable to just the change in offset as the new wheels would be slightly wider and the tires would have shorter sidewalls for less flex.

Whether or not the wheels will fit under the wheel arches is another story as I've got a 4.2 so I only have it and its wider wheel arches as a point of comparison which naturally isn't the same as a V6 model.

bmlee007

I just swapped out the winter wheels on my '02 2.7T for the 18x8 RS4 reps with 35mm offset from my recently traded A4. I'll be buying spacers for sure, as I can just fit the tip of my little finger between the inside of the tire and the spindle. You should have more clearance with 7.5 width, but be sure to check the clearance behind the tire before you head down the road.

Just Me

First, they should be fine. 2nd, the additional 10mm of offset places the wheel 10mm further out - 0.4". This is generally considered acceptable with almost no impact.

Now, when you move the steering wheels out, bad things DO happen. What's called the scrub radius increases. Its hard to describe without a pencil and paper, but you essentially place a (small) lever arm between the steering pivot point and the center of the wheel. Torque steer, bump steer increase, and all the forces on the hub are multiplied. The spring rate goes down and the damping efficiency goes down. None good.

But not to worry, audi sold lots of those with 35mm offsets - all the 17" equipped cars (4.2s, etc) and the snow tires for the 2.7t are 35mm. So its fine, so long as it clears the fenders.

G

monkeytronic

Offset is meaningless without taking wheel width into consideration.

FWIW increasing the wheel width from 7" to 7.5" means that the wheels' outboard dimension grows by half that amount which is 6mm (1/4") and at the same time decreasing the offset by 10mm nets a change in dimensions with the wheels extending outboard by 16mm and inboard towards the steering knuckle by 4mm.

Which is to say that one can't honestly say that all ET35 wheels will fit *all* applications without taking the width of the wheels into consideration.

Yes, it is true that 4.2s come with ET35 wheels factory stock...but they are 17x8s as in 8 inches wide...not 7.5 or 7 inches wide.

Speaking of which, I'm currently running a set of 18x8.5 ET35 wheels on the '02 4.2 and they come out flush with the car's wider wheel arches. But in order to do so, compared to 16x7 ET45 wheels, these wheels are 1.5" wider and, factoring in the 35mm offset, that all means that they sport a sizable increase in dimensions extending outboard by 29mm (1-1/8") and inboard by 9mm. And yet...they are ET35 wheels.

Just Me

for fit purposes, you are correct.

For geometry and steering purposes, you are incorrect. The only thing that matters - and in fact the reference point for the offset measurement, is the centerline of the wheel.

Even your examples talk only to fit and cosmetics - none of which was the subject of my post. Mine was about engineering and suspension geometry.

Oh, and 35mm 7.5 x 17s fit just fine. Lots of people run them today - S4 stockers for snows.

Everything i said stands.

G

Just Me

So, incidentally, your own calculations confirm what I'm saying.

You clearly know what the impact is of the offset on the inner, outer edges and therefore the centerline. But if i am not misreading your point, you find it odd that such a wheel has a 35mm offset. yet the math works perfectly.

So ignore the inner and outer edges and focus on the vector origin point for forces which is the centerline. After all the calculations its ...drum roll please..... 10mm :-)

The rest is simply interference avoidance.

G

rollerton

I recently got a set of 17x7.5 's off an A3- w/ ET of 54 I think? If I remember right the wine-glass wheels I removed were et46?
Anyway, clearance problems obviously. I really didn't want to dive into extended bolts and spacers so I swapped the 225/45 tires for 215/45.
Have about 8mm clearance to the spindle.. 800 miles and no rubbing. The difference in tire aspect is totally un-noticeable.
I'd much rather adjust the tire aspect very minimally to avoid spacers. As mentioned, a relatively OEM width (~7"?) wheel with smaller ET can get you into odd track/geometry and it's not a huge amount different with WIDE wheels/ spacer combo- as you're moving the effective wheel hub (bolting surface) away from the true hub (spacing the wheel OUT).
But...really,...it's splitting hairs. How much extra wear does it cause? I'd bet it's not really measurable. Just make your wheels fit!
beer!

Just Me

i agree that spacers are evil. Hwoever, you made it fit, but still have a steering geometry issue - in the opposite direction to the rest of the planet - pulled in. Only by a buillet's width, but narrowing the track would not be my first objective.....

G